1. Field of the Invention
The present invention relates to a conversion apparatus and, more particularly, to an alternating-current and direct-current conversion apparatus that is operated in a two-way manner.
2. Description of the Related Art
A conventional DC (direct-current) to AC (alternating-current) conversion apparatus in accordance with the prior art shown in FIG. 1 comprises a first converter 11, a high frequency transformer 12, a rectifier 13 and a second converter 14. The first converter 11 is electrically connected between a direct-current source 1 and the high frequency transformer 12. The high frequency transformer 12 is electrically connected between the first converter 11 and the rectifier 13. The rectifier 13 is electrically connected between the high frequency transformer 12 and the second converter 14. The second converter 14 is electrically connected between the rectifier 13 and an alternating-current source 2. In operation, the first converter 11 and the high frequency transformer 12 convert and transform the direct-current power of the direct-current source 1 into a high voltage direct-current power. Then, the rectifier 13 and the second converter 14 transform the high voltage direct-current power into a high voltage alternating-current power which is outputted from the alternating-current source 2. Thus, the direct-current power of the direct-current source 1 is directly converted into an alternating-current power which is used by the alternating-current source 2. However, the alternating-current power of the alternating-current source 2 cannot be directly converted into the direct-current power of the direct-current source 1 so that it is necessary to additionally provide an AC (alternating-current) to DC (direct-current) conversion apparatus.
A conventional AC (alternating-current) to DC (direct-current) conversion apparatus in accordance with the prior art shown in FIG. 2 comprises a first rectifier 15, a converter 16, a high frequency transformer 17, and a second rectifier 18. The first rectifier 15 is electrically connected between a mains power supply 3 and the converter 16. The converter 16 is electrically connected between the first rectifier 15 and the high frequency transformer 17. The high frequency transformer 17 is electrically connected between the converter 16 and the second rectifier 18. The second rectifier 18 is electrically connected between the high frequency transformer 17 and the direct-current source 1. In operation, the first rectifier 15 rectifies the alternating-current power of the mains power supply 3 into a direct-current power. Then, the converter 16 converts the direct-current power into a high frequency direct-current power. Then, the high frequency transformer 17 drops the voltage of and rectifies the high frequency direct-current power into a low voltage direct-current power which is outputted from the direct-current source 1. Thus, the alternating-current power of the mains power supply 3 is directly converted into a direct-current power which is used by the direct-current source 1. However, the direct-current power of the direct-current source 1 cannot be directly converted into the alternating-current power of the mains power supply 3 so that it is necessary to additionally provide a DC (direct-current) to AC (alternating-current) conversion apparatus.